In recent years, further increasing the speed of the color developing process has been demanded for the purpose of improving the photographic print productivity and also for other purposes, and various measures are devised in order to meet such the demand. A method known as one of such measures is the use of a color development accelerator in the case where the development of an exposed silver halide light-sensitive photographic material is developed by using an aromatic primary amine color developing agent. Examples of such the color development accelerator include those compounds as described in U.S. Pat. Nos. 2,950,970, 2,515,147, 2,496,903, 4,038,075, 4,119,462, British Pat. Nos. 1,430,998 and 1,455,413, Japanese Patent Publication Open to Public Inspection (hereinafter referred to as Japanese Patent O.P.I. Publication) Nos. 15831/1978, 62450/1980, 62451/1980, 62452/1980, 62453/1980 and 12422/1976, and Japanese Patent Examined Publication Nos. 12422/1976 and 49728/1980. However, as a result of our investigation, most of these compounds have been found out inadequate in the development acceleration effect, and even the rest showing an adequate development acceleration effect have been found disadvantageous in respect of producing a fog, thus being considered of no practical use.
Also, in order to accelerate the permeation of a color developing agent into a silver halide light-sensitive photographic material, various permeating agents have been examined. Of these agents, for example, benzyl alcohol is added to a color developer solution to accelerate the color development. This method is generally extensively used.
This method, however, has a drawback in some degree to rapid processing because it needs a processing at as high a temperature as 33.degree. C. for more than three minutes in order to obtain adequately high color-formed densities. In addition to the developing temperature, a method of increasing the pH concentration of a color developer solution to improve the color development is also proposed. This method, however, is also disadvantageous in respect that if, for example, the pH is raised to not less than 10.5, then the oxidation of a color developing agent is significantly accelerated, or the color developing agent is subject to pH changes because of no appropriate buffer solution being available, thus making it difficult to obtain stable photographic characteristics or increasing the dependence of the photographic characteristics upon processing time.
On the other hand, to make the color development more rapid, there is known a method as described in, e.g., U.S. Pat. No. 3,719,492, in which a color developing agent is in advance incorporated in a light-sensitive material.
This method, however, has the disadvantage that the silver halide light-sensitive photographic material containing a color developing agent is poor in the preservability tends to be fogged before being used, and further tends to be fogged also at the time of being color-developed.
In addition, to make the amine portion of such a color developing agent inactive, there are those methods in which the color developing agent is made in the form of, for example, a Schiff's salt to be incorporated into a light-sensitive material as described in, e.g., U.S. Pat. No. 3,342,559 and Research Disclosure No. 15159 in 1976. These methods, however, have the disadvantage that color development starts only after the alkali hydrolysis of the color developing agent, so that the color development is rather retarded.
Further, Japanese Patent O.P.I. Publication No. 64339/1981 discloses a method of incorporating a specific structure having 1-aryl-3-pyrazolidone into a silver halide color photographic material; and Japanese Patent O.P.I. Publication Nos. 144547/1982, 50532/1983, 50533/1983, 50534/1983, 50535/1983 and 50536/1983 disclose that the in advance incorporation 1-arylpyrazolidones into a silver halide light-sensitive photographic material enables to develop the photographic material in a very short period of time.
However, such techniques described in these publications are not necessarily considered satisfactory in respect of obtaining an adequate color developing speed and a dye image having high color densities, thus leaving room for further improvement.
Further, it is also known that the progress of the color development can be more sped up by using a silver chloride emulsion or a high silver chloride-content silver chlorobromide emulsion as the silver halide emulsion of a lightsensitive photographic material. Descriptions related to this technique can be found in, e.g., U.S. Pat. Nos. 4,183,756 and 4,225,666, and Japanese Patent O.P.I. Publication Nos. 26589/1980, 91444/1980, 95339/1983, 94340/1983, 95736/1983, 106538/1983, 107531/1983, 107532/1983, 107533/1983, 108533/1983, 125612/1983, and the like. The techniques described in these publications, although considered fairly satisfactory from the standpoint of their aptitude for rapid processing. have the disadvantage that they are still not good enough to provide adequate sensitivities, and particularly the emulsion shows significantly unstable changes in the sensitivity and gradation due to changes in the temperature at the time of exposure of the resulting light-sensitive material.
In the case where a labile sulfur compound and a gold compound are used in the chemical sensitization of a high silver chloride-content emulsion for the purpose of highly sensitizing the same, the above-mentioned changes in the sensitivity and gradation according to changes in the temperature at the time of exposure becomes even larger, which fact has been found out to be a large hindrance to practical use.
As a result of our continued investigation to solve the above-mentioned problems, we have now found the unexpected fact that where a specific high silver chloride-content emulsion is chemically sensitized by using the above-mentioned labile sulfur compound and gold compound, when a specific mercapto-type compound is further applied to the emulsion, a stable silver halide light-sensitive photographic material whose sensitivity and gradation are hardly affected by changes in the temperature at the time of exposure can be obtained. Thus the present invention has now been made.